The United States renewed a travel advisory for China on Thursday that warned American citizens could face arbitrary detention there, a move that came amid tense relations between the countries dominated by trade disputes and the recent American-requested arrest of a high-profile Chinese executive in Canada.

The rights of foreign citizens in China have received renewed focus because of public concern over the fate of an American family barred from leaving the country, Sandra Han and her two adult children, Victor and Cynthia Liu. The arrest in Vancouver last month of Meng Wanzhou, an executive of the Chinese tech giant Huawei, has also raised the specter of potential retaliatory arrests of Americans or Canadians in China.

The travel advisory issued by the State Department on Thursday was a routine renewal of a similar warning issued in January 2018. It urged Americans to “exercise increased caution in China” because of so-called exit bans, a legal tool the authorities there use to bar a person from leaving the country.

People subjected to a ban typically learn of its existence only when they try to leave China, and no method exists for them to determine when the ban has been lifted, the State Department said.

国务院称，被禁止离境的人往往是在试图离开中国时才得知该限制的存在，而且他们无法确定禁令何时已被解除。

The advisory warned that United States citizens under a ban have been “harassed and threatened” and “may be detained without access to U.S. consular services or information about their alleged crime.” They could also face “prolonged interrogations and extended detention for reasons related to ‘state security.’”

Canada’s leading newspaper, The Globe and Mail, reported Thursday that China had detained 13 Canadians since Ms. Meng’s arrest, a higher number than the three Canadians previously reported to have been detained after her arrest on Dec. 1.

But a spokesman for Canada’s foreign ministry said it did not have reason to believe that the arrests were retaliatory, although the spokesman said two of the Canadians — Michael Kovrig and Michael Spavor — were arrested for unspecified reasons of national security.

The State Department said China had used exit bans to compel foreign citizens to resolve civil disputes or to cooperate with investigations. Exit bans have also been used to turn foreigners into bait meant to lure other people, like fugitives, to the country.

国务院称，中国用禁止离境的做法迫使外国公民解决民事争端或配合调查。离境禁令还用于把外国公民变成诱饵，以诱引其他人前来该国，如外逃人员。

That appears to have been the motive behind the exit ban applied since last June to Ms. Han and her children, whose father, Liu Changming, is a former executive at a state-owned bank and accused of participation in a $1.4 billion fraud case. The children have said their father severed ties with the family in 2012.

Some people subjected to an exit ban have been imprisoned, including Ms. Han, a naturalized American citizen who was arrested and sent to a secret prison days after the family arrived in China in June to visit a sick relative.

Others, including her children, Mr. Liu, an American-born undergraduate at Georgetown University, and Ms. Liu, a naturalized American employed by the consulting firm McKinsey & Company in New York, are allowed to move freely within China. But they are forbidden to leave the country.

The Liu family’s case has drawn the attention of American officials, including Secretary of State Mike Pompeo, who criticized the practice of exit bans during a visit to China in October and mentioned the family to a top Chinese foreign policy official, Yang Jiechi, at a meeting in Washington in November.

“The investigative officers have made abundantly clear that neither my brother nor I am under any form of investigation,” Ms. Liu wrote. “We are being held here as a crude form of human collateral to induce someone with whom I have no contact to return to China for reasons with which I am entirely unfamiliar.”

Lu Kang, a spokesman for the Chinese Ministry of Foreign Affairs, brushed off the State Department’s warning on Friday, saying that China would “always adhere to the law in justly dealing with the tiny number of foreign nationals” suspected of crimes.